Support via

Introduction

Welcome to our load fault current calculator! This page will allow you to find the fault current through the cable to a load given:
  1. Voltage (V) [Single Phase or 3-Phase needs to be specified]
  2. Source fault current (kA)
  3. Cable size (mm^2) [Based on AS/NZ 3008]
  4. Cable Length (Km)
  5. Cable impedance (Ω) [Use design codes to find R_cable and X_cable]

Steps:
  1. Search AS/NZS 3008 and find resistance/km value at 75 degrees for the specified cable area (mm^2) in Table 35 of AS/NZS 3008 Electrical installations - Selection of cables
  2. Repeat for reactance/km on Table 30 for multi-core PVC circular conductors
  3. Multiply impedance/Km by length (remember values are in ohms/kilometre!)
  4. Input respective values and produce load fault value

Calculation

⬇️ Inputs



V_1P
:240volts



I_S_fault
:10kA



R_cable
:16.5



X_cable
:0.111ohms



Length
:0.3km


⬆️ Outputs



I_1P_load fault
:24.1833466ampere



I_3P_load fault
:48.3666933ampere




Z_1P_source
:0.023960739ohms



Z_cable
:4.95011201ohms


💬 We'd love your feedback on this template! It takes 1min


Explanation

Short circuit fault current is the amount of current that flows through a circuit when a short circuit occurs. It is an important factor to consider in electrical engineering, as it determines the size of protective devices such as circuit breakers and fuses.
When a short circuit occurs, the resistance in the circuit drops to nearly zero, causing the current to increase significantly. The short circuit fault current is the maximum current that will flow through the circuit at the point of the fault. Calculating the short circuit fault current is important to ensure that the protective devices are properly sized to handle the high current.

Single Phase fault current:

Relation between 3-Phase and Single-Phase voltage:

3 Phase fault current:

Source Impedance:


Cable Impedance:

Where:



Additional Resources

To calculate full load current in a component, a generator, as well as calculating many other parameters, try out our other calculators!
  1. 🔗 Full Load Current
  2. 🔗 Generator Load Current

💬 Got 1min to provide feedback on this template? Click here